The present invention relates to pod structure for housing jet propulsion engine for use on airplanes, and more particularly, to a pod attached to a wing-supported strut that has common structure for housing a variety of different turbofan jet propulsion engines.
A number of different manufacturers build turbofan jet propulsion engines that have approximately the same thrust rating. For example, Pratt & Whitney is designing and will manufacture a high bypass ratio turbofan jet propulsion engine having a rating of about 25,000 pounds of thrust. The Pratt & Whitney engine is denominated the JT10D. The General Electric Company has a similar engine denominated CFM56, while Rolls Royce has a similar engine designated RB235. All three engines will provide approximately the same power output. However, each of the engines has been independently designed and will be independently manufactured, resulting in overall dimensions that will vary among the engines. Examples of dimensions that will vary include the fan casing inlet and outlet diameters, the engine length, and longitudinal dimensions of the fan case. In addition, each of the engines will require a slightly different fan nozzle and primary (turbine) nozzle area that is matched to the engine's unique operating characteristics.
In the past, pods to house the jet propulsion engines have been independently designed and tailored to the unique dimensional characteristics, inlet sizes, and nozzle sizes, of each of the several engines that may be requested by a customer. The non-recurring development costs for a pod to house a particular engine currently range from fifty to ninety million dollars. Thus, if a pod is to be designed to each of three different engines, these non-recurring, development costs must be trebled. As a result, the need has arisen to significantly reduce these high developmental costs. One solution to cost reduction would be to select a single engine for incorporation into a new aircraft design. This solution, however, is impractical as purchasers of a new airplane may have a fixed preference for engines manufactured by one or another of the several engine manufacturers. Thus, selection of only one engine would necessarily and undesirably limit the range of customers who might acquire a given airplane.
Accordingly, it is a broad object of the present invention to reduce the non-recurring costs for developing a pod for housing a turbofan jet propulsion engine while developing a pod or pods that will accomodate engines from different manufacturers. It is a further object of the present invention to provide a pod for housing a variety of turbofan jet propulsion engines that has a large proportion of common components and that can be easily adapted to receive the variety of engines. A further object of the present invention is to provide a pod for housing a variety of jet propulsion engines while maintaining the development costs in the proximity of costs for developing a pod specifically for a given engine.